This Lee Filters SW150 Hard Grad Set is a set of three 150x170mm filters that are compatible with a separately available Lee Filters SW150-series filter holder and are suitable for both film and digital photography. Lee Grad ND filters are part clear, part neutral density, and make it possible to balance the light intensity in one part of a scene with another. Generally soft grads are best used on images of woodland, mist or interiors where as hard grads are better suited to any image with a horizon line or hard transition between the sky and foreground. This hard grad set contains grades of .3 (1 stop), .6 (2 stops), and .9 (3 stops). Lee graduated resin filters are 150 x 150mm x 2mm thick. The additional length allows for adjustment of the filter within the holder. All Lee NDs are meticulously hand-dyed each filter represents up to an hour of skilled work, as they are dipped in and out of baths of dye and results continuously monitored. You can stack any number of NDs together with other filters, to customise your Lee filter setup for any lighting situation.